1. Technical Field
The present invention relates to a paper-folding station for sheets of paper generally used for assembling books, magazines, and the like.
2. Description of the Prior Art
As known, paper sheets can be folded for manufacturing parts of books and magazines by means of so-called “pocket” folding stations, which allow the sheet to be folded transversely to the sheet-feeding direction along parallel lines. A paper-folding station generally comprises one or more folding units each having a triad of rollers arranged in square, two adjacent of which feed the sheet into a thin chamber, known as “pocket” or “buckle”, having an adjustable thickness, with an inlet mouth and an adjustable transversal barrier which cause the sheets to stop and to bend into the shape of a groove below the inlet mouth. The groove progressively lengthens up to meet two adjacent folding rollers of the triad, which pinch the bottom of the groove and form the fold on the sheet.
The inlet mouth of the buckle is delimited between a lower profile, which must be as near as possible to, and along the tangent of, the outer folding roller, and an upper profile which also functions as a guide for a correct formation of the groove on the sheet. Since an accurate positioning of the profiles with respect to the rollers is critical for achieving an accurate and regular fold, as well as for reducing the risk of jamming, in the known paper-folding stations an accurate construction and assembling of the buckle is required, which buckle, consequently, is very fragile to use as well as expensive to manufacture, also because it must be made movable and removable from the structure of the machine which supports the folding rollers, in order to allow the operator either to carry out the required adjustments or to remedy any jamming of the paper.
Furthermore, in the known paper-folding stations, adjusting the position of the inlet mouth is an awkward operation because, when the buckle is in its operative position, it is not possible to control the exact position of the inlet mouth relative to the rollers, so that external rulers divided into millimeters must be used, which rulers, however, have a very low resolution.